"The yellow dress."
Translation:Den gule kjole.
After the definite article or a possessive, the adjective takes it's "e-form". For example
"Et gult hus" = A yellow house
"Det gule hus" = The yellow house
"Mit/Dit/Sørens gule hus = My/Your/Søren's yellow house
"Huset er gult"=The house is yellow
"Mit/Dit/Sørens hus er gult"=My/Your/Sørens house is yellow
Following on from my above examples, "gul" is used in the same places I used "gult", but used for singular, common gender nouns:
En gul bil = A yellow car
Den gule bil = The yellow car
Min/Din/Sannes gule bil = My/Your/Sanne's yellow car
Bilen er gul = The car is yellow
Min/Din/Hendes bil er gul = My/Your/Her car is yellow